View all publications

Section 1. Introduction

1.1 What is the purpose of these guidelines?

These guidelines provide advice on how public health risk associated with cyanobacteria in recreational waters can be managed. They have been developed in response to requests for best-practice advice from regional resource management and health agencies, and are intended to:

  • help these agencies develop monitoring protocols appropriate for local conditions and circumstances
  • encourage the adoption of a nationally unified approach to managing cyanobacterial risk in water used for recreational purposes.

1.2   What does this document cover?

These guidelines set out a monitoring framework for establishing the public health risk from cyanobacteria associated with contact recreation in lakes (mainly planktonic cyanobacteria) and rivers (mainly benthic cyanobacteria).

They do not cover the public health risk associated with recreation in coastal or estuarine waters, food gathering (eg, shellfish) or drinking waters. Further information on cyanobacteria in drinking water supplies can be found in the Ministry of Health’s Drinking-water Standards for New Zealand 2005 (Ministry of Health, 2005b). The Drinking-water Standards set out provisional maximum allowable values for seven cyanotoxins. The accompanying Draft Guidelines for Drinking-water Quality Management for New Zealand (Ministry of Health, 2005a) provide information to water supply authorities on how to monitor and manage water supplies for cyanobacteria and their toxins, including sampling requirements, recommended actions in response to threshold breaches, and treatment options. These documents are available at:

For further advice on levels of cyanotoxins in aquatic organisms (eg, shellfish), contact the New Zealand Food Safety Authority:

Finally, this document does not provide explicit guidance for managing the impacts of cyanobacterial events on other environmental values such as ecosystem health and amenity. There are guidelines available that are more appropriate for this, such as the New Zealand Periphyton Guideline (Biggs, 2000).

1.3   Who should use these guidelines?

The New Zealand Guidelines for Cyanobacteria in Recreational Fresh Waters have been developed for staff and agencies involved in monitoring and reporting water quality for human recreation. Specifically, these are:

  • science staff within regional councils and unitary authorities who routinely monitor the state of the environment
  • public health officers in district health boards and public health units who assess and communicate environmental health risks to the public
  • operational staff within territorial authorities who are responsible for alerting people to dangers in public spaces.

More guidance on the roles and responsibilities of these staff and agencies is provided in Section 2.4.

These guidelines may also be of interest to the wider environmental science and resource management community. For example, policy and planning staff within councils may find some of the background material on the environmental causes of bloom occurrence useful for fresh water policy development (eg, the setting of environmental flows). However, the guidelines should not be used for resource consenting work. For example, guideline thresholds should not be used as the basis for establishing conditions for discharge consents, although they may be used as a component of the decision-making process.

The guidelines are a companion to the existing Microbiological Water Quality Guidelines for Marine and Freshwater Recreational Areas (Ministry for the Environment and Ministry of Health, 2002).

1.4   Status of this guidance

This document is an interim version of the guidelines. This version has been released for trial use by monitoring and health agencies until the end of the 2011/12 summer, at which point it will be revised, based on feedback from practitioners. The guidelines will subsequently be released as a final version.

It is important to note that the guidelines are not mandatory. They constitute a recommended approach that is considered best practice for many management circumstances, given current understanding of cyanobacterial risks in New Zealand fresh waters. However, there are still gaps in scientific knowledge and health risk management that require local judgements to fill. Also, local decisions about whether to follow the guidelines’ approach should ultimately result from consideration of site-specific factors (such as resource availability, historical understanding of local bloom conditions), as well as the guidance offered in this document.

The word ‘should’ has been used throughout the guidelines to describe recommended actions by monitoring and health agencies. This is intended to convey that the action being described is considered best practice as a general rule. Local knowledge and historical data should be used when establishing monitoring programmes.